JPH0541396U - Inverter device - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the wiring inductance connecting the DC power supply to the inverter as much as possible and to make it a large-capacity inverter structure. [Structure] A smoothing capacitor of a three-phase inverter and a connecting conductor of an inverter body are insulated from each other by a bar wiring to form a connecting plate having a plate structure in which two sheets are stacked.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an inverter device, and more particularly, to connection between a plurality of capacitors used for the inverter device and a plurality of main transistors of an inverter body.

[0002]

[Prior Art]

 A conventional inverter device is shown in FIGS. 4 and 5. 4 is a circuit diagram thereof, and FIG. 5 is a connection diagram thereof. In FIGS. 4 and 5, a DC power source is formed by the AC power source 1, the rectifying circuit 2 and the smoothing capacitors (hereinafter simply referred to as capacitors) 3a and 3b. The inverter main body 4 to which direct current is supplied from the direct current power source is composed of three sets of main transistors 4a, 4b and 4c as main switching elements, each of which has two transistors built therein. Reference numeral 5 is a snubber circuit. This snubber circuit 5 has a resistor 5b and a diode 5a connected in parallel, and a capacitor 5c connected in series to the snubber circuit 5. The snubber circuit 5 is intended for overvoltage protection of the inverter body 4. . Note that U, V, and W are three phases of the AC power supply, C is the collector side of the main transistor, and E is the emitter side. The inverter body 4 and the snubber circuit 5 described above are well known and widely used in the past.

In such a configuration, the main transistors 4a, 4b, 4c perform a switching operation at a high frequency to carry and cut off a current. The short-time pulse current flowing into the main inverter 4 flows from the anode side of the capacitors 3a and 3b through the inverter 4 and from the load machine 7 to the cathode side of the capacitors 3a and 3b. By these control signals, the main transistors 4a, 4b, 4c which operate as an inverter operate at high speed and shut off. As described above, when the main transistors 4a, 4b, 4c are turned off in a very short time, the shorter the off-time is and the larger the off-state current is, the moment the main transistors 4a, 4b, 4c are cut off. A voltage is generated across the transistors 4a, 4b, 4c due to the wiring inductance. This is well known, and if the surge voltage generated when this is turned off becomes abnormally high, the main transistor may be damaged.To solve this, the main transistor cuts off the surge voltage generated. A snubber circuit 5 is generally provided for the purpose.

[0004]

[Problems to be solved by the device]

 However, as the capacity of the inverter increases, the overall structure of the device also increases. Therefore, the wiring around the transistors that make up the inverter becomes long, and the wiring inductance cannot be ignored. In other words, when the main transistor is cut off due to the inverter operation, a surge voltage is generated across the transistor due to the wiring inductance, and in some cases it becomes impossible for the snubber circuit to fully absorb the surge voltage. It may exceed the allowable value of the transistor and lead to destruction. As a solution to such a problem, it is necessary to reduce the conduction path inductance of the transistor of the inverter as much as possible. That is, it is desirable to make the wiring inductance between the main transistors 4a, 4b, 4c of the inverter body 4 and the capacitors 3a, 3b substantially zero, and the distances lp and ln between the filter capacitor 3 and the main transistors 4a, 4b, 4c. It is most effective to make the shortest wiring with a conductor bar. However, as shown in Fig. 5, in the conventional case, the conductor bars A1 and A2 were connected over a long distance.

[0005]

[Means for Solving the Problems]

 The present invention was made by paying attention to this bar wiring. Instead of the conductor bar as described above, a conductor integrating a capacitor, an anode and a cathode is provided on the collector side C and the emitter side of the main transistor of the inverter body. It is connected so as to cancel the inductance of E. Note that this also includes sandwiching an insulator between the two conductors.

[0006]

With such a configuration, the connection between the capacitor 3 and the inverter body 4 is simple, and the conducting area of the conductor can be increased. In addition, since the conductor structure is a superposed structure, it is possible to suppress the off-time voltage surge of each main transistor on the inverter side.

[0007]

【Example】

 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a front view of FIG. 1, and the same reference numerals as those in FIG. 1 and 2, smoothing capacitors (hereinafter simply referred to as capacitors) 3a, 3b and main transistors 4a, 4b, 4c of the inverter body are connected by connecting conductors B1, B3. As shown in FIG. 2, the connection conductors B1 and B3 have a structure in which a thin insulator B2 is sandwiched between the plate-shaped conductors B1 and B3, and one side of this conductor is on the anode side of the smoothing capacitors 3a and 3b. In addition, the conductor on the other surface is connected to the cathode side of the capacitors 3a and 3b, and the cooling fins 6 are attached to the lower portions of the main transistors 4a, 4b and 4c. The insulator B2 is an insulator that can withstand this inverter circuit. In such a structure, the charging and discharging currents of the capacitors 3a and 3b flow in the opposite directions with the conductors B1 and B3 interlinking each other. Therefore, the magnetic fluxes generated by the current flowing through the interlinked conductors cancel each other out, and the equivalent inductance of these conductors becomes zero. FIG. 3 is a front view similar to FIG. 2 showing another embodiment of the present invention, which has a conductor shape different from that of FIG. 1, particularly the mounting surfaces of the capacitors 3a, 3b and the main transistors 4a, 4b, 4c. If the heights do not match, the connecting conductors B1 and B3 and the insulator B2 are bent to connect the capacitors 3a and 3b to the main transistors 4a, 4b and 4c.

[0008]

[Effect of the device]

 As described above, according to the present invention, when the inverter is operated by the inverter device, the DC power supply, which is the source of the inverter, that is, the inductance between the capacitor and the main transistor of the inverter body is increased by the conventional conductor bar connection. Reduce to width. Therefore, when the inverter device according to the present invention is operated under load, the inductance from the direct current power source, which is the source of the inverter, to the main transistor of the inverter is greatly reduced as described above, and the main silane transistor is cut off at high speed. However, the surge voltage is lower across the transistor than in conventional inverters. Therefore, the capacity of the snubber circuit surge absorbing capacitor can be reduced, and the snubber can be made smaller or smaller, and the economic effect is great. Further, the parallel connection of the main transistors forming the inverter can be easily performed by the connecting conductor of the present invention. Even when the main transistor and capacitor with large current capacity are connected in parallel, the current area of the connecting conductor can be increased, so it can be applied to large inverters.

[0009]

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an inverter device of the present invention.

FIG. 2 is a front view of FIG.

FIG. 3 is a front view showing another embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional example.

FIG. 5 is a connection diagram thereof.

[0010]

[Explanation of symbols]

 1 AC power supply 2 Rectifier circuit 3a Smoothing capacitor 3b Smoothing capacitor 4 Inverter body 4a Main inverter 4b Main inverter 4c Main inverter 5 Snubber circuit 6 Cooling fin 7 Load machine B1 Conductor B2 Insulator B3 Conductor A1 Conductor bar A2 Conductor bar

Claims (1)

[Scope of utility model registration request] 1. A rectifier for converting an AC voltage into a DC voltage, an inverter body for converting the DC voltage from the rectifier into an AC voltage by a high frequency switching operation of a plurality of main switching elements, and the rectifier and the inverter body. A plurality of smoothing capacitors are provided between the smoothing capacitors, and a conductor is connected from each of the plurality of smoothing capacitors to the anode side and the cathode side of the iterverter body so as to cancel the inductance at both ends of the main transistor. An inverter device characterized by being worn.